Auto-injector with active agent container latching

ABSTRACT

In an elongated casing, an active agent container connected to an injection needle can be shifted axially by a spring force. Auto-injectors which are sold or distributed filled and with the springs tensed have to be provided with a needle protecting cap to ensure the sterility of the injection needle. When such a needle protecting cap is removed as preparation for using the auto-injector, a tensile force can be exerted on the active agent container. Therefore, the active agent container comprising the injection needle must be prevented from being undesirably pulled forwards. At least one latching tongue prevents the active agent container from being prematurely shifted with respect to the casing, by abutting a flange arranged on a sliding sleeve which accommodates the active agent container. When the auto-injector is placed onto a person&#39;s skin, a needle protecting tube is shifted into the casing, forcing the latching tongue away from the flange and, thus, freeing the travel path for needle movement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Swiss application No. CH 2186/03,filed on Dec. 18, 2003, the content of which is incorporated byreference herein in its entirety.

BACKGROUND

The invention relates to devices and methods for the administration ordelivery of substances, including the administration of medicinalsubstances to patients. More particularly, it relates to injection orinfusion devices and methods, and to an auto-injector for automaticallyinjecting an active agent. In one embodiment, the auto-injectorcomprises an elongated casing, an injection needle which can be shiftedaxially in the casing and is connected to an active agent container, apiston which can be shifted in the active agent container for thepurpose of delivering the active agent, and a needle protecting tubewhich can be shifted relative to the casing.

Auto-injectors are known in many different embodiments. They serve toadminister injections, in particular by a patient him or herself. Whenused, an injection needle is automatically inserted, in the majority ofcases by means of a spring force, and then an active agent is injected.Many reusable auto-injectors are known and also those which, once used,are partially or completely thrown away. Auto-injectors which are soldor distributed filled and with the springs tensed have to be providedwith a needle protecting cap in order to be able to ensure the sterilityof the injection needle. Since this needle protecting cap preferablyencloses the active agent container connected to the injection needle,forming a seal, a certain tensile force is necessarily exerted on theactive agent container as the needle protecting cap is removed inpreparation for using the auto-injector.

SUMMARY

In one embodiment, the present invention addresses the object ofpreventing an active agent container, comprising an injection needle,from being undesirably moved, e.g., pulled forward, for example whenremoving a needle protecting cap.

This object is addressed in accordance with one embodiment of theinvention by providing an injection device with a latching member that,in a latching position, prevents the active agent container from beingshifted with respect to the casing of the device, and by providing thatthe latching member can be moved to a release position, in which itallows the active agent container to be shifted with respect to thecasing, by shifting a needle protecting tube into the casing. In oneembodiment, the latching member is preferably fixed and/or locked in thelatching position by the needle protecting tube.

In one embodiment, the present invention comprises an automaticinjection device comprising an elongated casing, and an active agentcontainer connected to an injection needle, wherein the container can beshifted axially by a spring force. Such auto-injectors which are sold ordistributed filled and with the springs tensed have to be provided witha needle protecting cap to ensure the sterility of the injection needle.When such a needle protecting cap is removed as preparation for usingthe auto-injector, a tensile force can be exerted on the active agentcontainer. Therefore, the active agent container comprising theinjection needle should be prevented from being undesirably pulledforwards. At least one latching tongue prevents the active agentcontainer from being prematurely shifted with respect to the casing, byabutting a flange arranged on a sliding sleeve which accommodates theactive agent container. When the auto-injector is placed onto a person'sskin, a needle protecting tube is shifted into the casing, forcing thelatching tongue away from the flange and, thus, freeing the travel pathfor needle movement.

The present invention not only has the advantage that the active agentcontainer remains in position in the auto-injector when the needleprotecting cap is removed, but also that the auto-injector is preventedfrom being intentionally or unintentionally triggered until the needleprotecting tube has been shifted into the casing.

In accordance with a preferred embodiment of the invention, the latchingmember is formed as at least one elastically flexible latching tongue.The tongue can be arranged on the casing itself or, in some preferredembodiments, on a latching sleeve mounted in the casing and formedintegrally with the latching sleeve. These measures make it easier tomanufacture the components from plastic in an injection mouldingprocess, but alternatives exist, including forming the tongue and sleeveseparately and then operably coupling them.

In one embodiment, the latching member preferably prevents the activeagent container from being shifted with respect to the casing byabutting a flange arranged on a sliding sleeve which accommodates theactive agent container. As it is shifted into the casing, the needleprotecting tube forces the latching member away from said flange. Thisdesign is simple and operationally reliable.

In accordance with another preferred embodiment of the invention, thelatching member comprises a surface which runs or extends obliquely withrespect to the longitudinal axis of the auto-injector and abuts asurface, likewise running or extending obliquely with respect to thelongitudinal axis of the auto-injector, on the sliding sleeve whichaccommodates the active agent container. In some embodiments, theoblique surfaces of the latching member and the sliding sleeve ideallyrun parallel to each other. In some preferred embodiments, the obliquesurfaces are each arranged on facing sides of the latching member andthe sliding sleeve, such that the tip of the oblique surface of thelatching member is provided on a surface of a latching sleeve, thesurface pointing outwards from the auto-injector.

In the latching position, the oblique surfaces abut each other and thelatching member is held in this position by the needle protecting tube.When the needle protecting tube is shifted into the casing, the latch isreleased. As soon as pressure is exerted on the sliding sleeve, so as toadvance the active agent container comprising the needle for injecting,the oblique surface of the latching member slides outwardly along theoblique surface of the sliding sleeve, such that the sliding sleeve canbe advanced. The latching member is therefore moved or forced out of thelatching position by the sliding sleeve.

In accordance with another embodiment of the invention, a needleprotecting cap is provided which preferably fulfils a double function inthat it prevents the needle protecting tube from retracting into thecasing when it is placed on the auto-injector. To this end, the needleprotecting cap preferably comprises an inner sleeve reaching over theactive agent container and an outer sleeve reaching over the needleprotecting tube.

BRIEF DESCRIPTION OF THE DRAWINGS

(Each of the first seven figures depicts a longitudinal section throughone embodiment of an auto-injector in accordance with the presentinvention, wherein a different operational state is depicted in eachfigure).

FIG. 1 depicts the condition on delivery;

FIG. 2 depicts the state in which the auto-injector is unlocked;

FIG. 3 depicts the state in which the auto-injector is placed on thepoint of injection;

FIG. 4 depicts triggering;

FIG. 5 depicts the end of injecting;

FIG. 6 depicts the end of delivering the active agent;

FIG. 7 depicts the state once used;

FIG. 8 depicts another embodiment of an auto-injector in accordance withthe invention, in the latching position;

FIG. 9 depicts the auto-injector embodiment of FIG. 8 in a releasingposition;

FIG. 10 depicts the auto-injector embodiment of FIG. 8 in a position inwhich the needle has been injected; and

FIG. 11 depicts the auto-injector embodiment of FIG. 8 in a lockingposition in which the needle protecting tube is latched.

DETAILED DESCRIPTION

The drawings depicts one exemplary embodiment of an auto-injector inaccordance with the present invention. The depicted auto-injector has acasing “C” comprised of a front casing part 1 and a rear casing part 2,wherein the two casing parts are joined together by a connection 3. Ifthe auto-injector is a refillable auto-injector, the connection 3 isreleasable, for example, it may comprise a threaded connection. If,however; the auto-injector is a disposable, the connection 3 can befixed, for example, by a fused connection, adhesive connection orlatching connection. On the left in the figures, a needle protectingtube 4 can be seen which can be shifted axially in the front casing part1, as will be described in more detail below. A sliding sleeve 5 whichcan be shifted axially is guided in the needle protecting tube 4 via itsfront end and in the front casing part 1 via a flange 6 formed on itsrear end. The sliding sleeve 5 accommodates an ampoule-like active agentcontainer 7, in the interior of which a piston 8 can be shifted axiallywith the aid of a piston rod 9, for the purpose of delivering the activeagent. At its front end, the active agent container 7 is provided withan injection needle 10.

A locking member in the form of a locking sleeve 24 is mountedexternally on the sliding sleeve 5. At least one locking tongue 25protrudes elastically outwards from the locking sleeve 24 and in theoperational state in accordance with FIG. 1 abuts an inner heel 27 ofthe needle protecting tube 4. A cavity 26 which is formed in the needleprotecting tube 4 and into which the locking tongue 25 protrudes isconnected to the heel 27. The function of the locking sleeve 24 and thelocking tongue 25 will be set forth further below. A guiding sleeve 11is arranged in the rear casing part 2, such that it can be shiftedaxially. A driving part 12, which protrudes backwards out of the guidingsleeve 11 and abuts an end flange of the guiding sleeve 11 via latchingprojections 13, is situated in the guiding sleeve 1. The driving part 12contacts the piston rod 9 and is biased against it by a driving spring14.

In FIG. 1, the auto-injector is depicted in its latched position. Thisposition is useful for the delivery, shipment, sale or storage of theauto-injector since it secured against being intentionally orunintentionally activated and is protected from contamination. A needleprotecting cap 15 on the side of the injection needle 10 serves thispurpose and has an outer sleeve 16 reaching over the front casing part 1and the needle protecting tube 4 and an inner sleeve 17 reaching overthe injection needle 10 and the front end of the active agent container7 which encloses it, forming a seal, and thus ensures that the injectionneedle 10 is clean and sterile. In addition, the attached needleprotecting cap 15 also secures the auto-injector against beingintentionally or unintentionally triggered, by preventing the needleprotecting tube 4 from being touched or shifted.

A securing cap 18, which comprises a securing pin 19 in its centre, isplaced on the rear end of the auto-injector, on the right in thefigures. The securing pin 19 protrudes between the latching projections13 of the driving part and thus reliably prevents an injection frombeing triggered. In order to prepare the auto-injector for use, theneedle protecting cap 15 and the securing cap are removed. It is clearthat when the needle protecting cap 15 is removed, a tensile force isexerted on the active agent container 7 as a result of the staticfriction between the inner sleeve 17 and the active agent container 7.Consequently, the active agent container 7 must be prevented fromleaving its position (e.g., being undesirably moved or pulled forward)in the auto-injector when the needle protecting cap 15 is removed.

For this purpose, a latching sleeve 20 is mounted in the front casingpart such that it cannot move axially and at least one latching tongue21 is arranged on the latching sleeve 20. Three latching tongues 21 arepreferably provided in one embodiment, arranged or distributedsymmetrically around the circumference of the latching sleeve. As FIG. 1clearly shows, the free end of the latching tongue 21 abuts the flange 6of the sliding sleeve 5 and thus prevents the sliding sleeve 5 frombeing pulled forwards together with the active agent container 7arranged in it.

FIG. 2 shows the auto-injector after the needle protecting cap 15 andthe securing cap 18 have been removed as described above. The latchingmember 20 is still in the latching position and the latching tongue 21prevents the active agent container 7, comprising or carrying theinjection needle 10, from being slid forward. In addition, at the thenopen end, the needle protecting tube 4 creates a distance which preventsthe injection needle 10 from being touched or at least makes itdifficult to touch the injection needle 10. The needle protecting tube 4is held in this position by the force of a spring 22 which is clampedbetween the rear end of the needle protecting tube 4 and the rear casingpart 2.

FIG. 3 shows the auto-injector in a position which it assumes when it ispressed onto the skin of a patient but has not yet been triggered. Theneedle protecting tube 4 has been shifted backwards into the casing ascompared to the position of FIG. 2, compressing the spring 22, such thatthe tip of the injection needle 10 is then situated slightly above theskin of the patient. FIG. 3 also shows that the needle protecting tube 4shifted backwards has forced the latching tongue 21 outwards, which thenexposes the flange 6 of the sliding sleeve 5. As compared to FIG. 2, itcan be seen that a flange 23 formed internally in the rear part of theneedle protecting tube 4 then abuts the front facing side of the guidingsleeve 11. It should be noted that the needle protecting tube stillprotrudes out of the front casing part 1 by a remaining amount at thefront. However, as compared to FIGS. 1 and 2, it should be clear thatthe needle protecting tube 4 has slid the locking sleeve 24 somedistance backward on the sliding sleeve 5.

FIG. 4 shows the auto-injector at the moment of triggering. Proceedingfrom the state depicted in FIG. 3, the user has pressed theauto-injector slightly harder onto the skin, such that the needleprotecting tube 4 has been shifted into the casing by the remainingamount mentioned above, wherein the flange 23 has shifted the guidingsleeve 11 backwards in the rear casing part 2 by the remaining amountand the latching projections 13 have been moved into the region of atriggering ring 28 arranged in the rear end of the rear casing part 2.The triggering ring 28 has contacted and/or pressed the latchingprojections 13, formed on elastic arms of the driving part, far enoughagainst each other that they are then pulled through the end opening ofthe guiding sleeve 11 by the force of the driving spring 14. The forceof the driving spring 14 then acts, unobstructed, on the piston 8 viathe piston rod 9, the piston 8 in practice abruptly increasing thehydraulic pressure in the active agent container 7. This pressure slidesthe active agent container forwards, such that the injection needle 10penetrates into the skin of the patient. Since the diameter of thepassageway in the injection needle 10 is comparatively small, at most avery small amount of the active agent can exit the injection needle 10in this short period of time between triggering and the injection needle10 penetrating into the skin.

The injection stroke is complete when the flange 6 of the sliding sleeve5 abuts the end of the needle protecting tube 4 and/or the end of thelocking sleeve 24. FIGS. 5 and 6 show the auto-injector in the positionin which the injection needle 10 is inserted or injected, wherein FIG. 5shows the operational state at the beginning of delivering the activeagent and FIG. 6 shows the state of the auto-injector after the activeagent container 7 has been completely emptied. When the operationalstate in accordance with FIG. 6 has been reached, the user retracts theauto-injector in order to remove the injection needle 10 from his skin.

FIG. 7 shows the operational state after the injection needle 10 hasbeen removed from the skin of the patient. The needle protecting tube 4was shifted back into its initial state by the force of the spring 22 assoon as the auto-injector was lifted from the skin of the patient. Itthen mainly serves to substantially cover the injection needle andprotect the user and other persons from injuries from the injectionneedle 10. Consequently, the needle protecting tube 4 must be preventedfrom being shifted relative to the injection needle 10 such that theinjection needle 10 protrudes out of the needle protecting tube 4. Thistask is accomplished by the locking tongue 25, which is formed in thelocking sleeve 24. While the needle protecting tube 4, as mentioned, hasbeen shifted forwards by the spring force, the locking sleeve 24maintains its position on the sliding sleeve 5 as a result of a latchtongue 29 formed on the sliding sleeve 5, which then protrudes into acavity of the locking sleeve 24 in the position in accordance with FIG.7 and thus fixes it in place on the sliding sleeve 5.

As can clearly be seen in FIG. 7, the free end of the locking tongue 25at the rear end of the needle protecting tube 4 then protrudes into itspath. Thus, the needle protecting tube 4 cannot be retracted without thelocking sleeve 24, the sliding sleeve 5 and the active agent container 7together with the injection needle 10, being shifted backwards relativeto the front casing part 1 and the rear casing part 2, against the forceof the driving spring 14. Thus, the injection needle 10 maintains itsrelative position with respect to the needle protecting tube 4 and theinjection needle 10 and is reliably prevented from being intentionallyor unintentionally touched. This solution has the advantage that theaxially directed force to be absorbed by the locking tongue 25 neverexceeds the force of the driving spring 14, irrespective of how hard onepresses against the front end of the needle protecting tube 4.

FIGS. 8 to 11 show another embodiment of an auto-injector in accordancewith the present invention. In these figures, identical elements andelements having substantially the same function are denoted using thereference numerals from FIGS. 1 to 7. In this embodiment, the latchingtongue 21 is guided by means of surfaces on the latching tongue 21 andthe sliding sleeve 5, the surfaces running or extending obliquely withrespect to the longitudinal axis of the auto-injector. The latchingtongue 21 for latching the active agent container or the sliding sleeve5 and the locking tongue 25 for latching the needle protecting tube 4are also both arranged on the latching sleeve 20. In some preferredembodiments, the latching tongue 21 and the locking tongue 25 are formedintegrally with the latching sleeve 20. In some embodiments, multiplelatching tongues 21 and locking tongues 25 can be provided on thelatching sleeve 20.

FIG. 8 shows a latching member in the form of a latching sleeve 20 whichcomprises a latching tongue 21 which comprises a surface 30 running orextending obliquely with respect to the longitudinal axis of theauto-injector, on its facing side. The tip of the oblique surface 30abuts the outer side of the latching tongue 21. The sliding sleeve 5comprises a cavity 31 into which the latching tongue 21 protrudes in thelatching position. The edge of the cavity 31 opposite the obliquesurface 30 of the latching tongue 21 comprises an oblique surface 30′which runs or extends generally parallel to the oblique surface 30 ofthe latching tongue 21. (In some embodiments, an oblique surface couldbe provided directly on the active agent container 7, such that thesliding sleeve 5 can be omitted.) The two oblique surfaces 30 and 30′come to rest on each other. The needle protecting tube 4 is at leastpartially arranged between the latching sleeve 20 and the sliding sleeve5, wherein the latching tongue 21 protrudes through a cavity in theneedle protecting tube 4 into the cavity 31 of the sliding sleeve 5. Apart 32 of the needle protecting tube 4 overlaps the abutting point ofthe oblique surfaces 30 and 30′, such that the latching tongue 21 islocked in the latching, latched or lacked position. In FIG. 8, a lockingtongue 25 is also arranged on the sliding sleeve 5, on the side oppositethe latching tongue 21. The locking tongue 25 protrudes into a cavityopposite it, in the needle protecting tube 4.

FIG. 9, generally analogous to FIG. 3, shows the auto-injector in arelease position in which the needle protecting tube 4 is slid into thecasing “C”. In this position, the part 32 of the needle protecting tube4 has been retracted from the overlapping area of the oblique surfaces30 and 30′. The latching tongue 21 can then be moved into the cavity 31of the needle protecting tube 4. The movement can be caused by a bias onthe elastic latching tongue 21. In some preferred embodiments, however,the latching tongue 21 is slid outwards into the cavity by the pressureexerted by the driving spring 14, which acts on the oblique surface 30.

FIG. 10, generally analogous with FIG. 5, shows the auto-injector in aposition in which the active agent container 7 is advanced relative tothe casing “C” and the injection needle 10 is injected into a tissue.The sliding sleeve 5 has been advanced together with the active agentcontainer 7 in a distal direction along the latching sleeve 20, whereinthe latching tongue 21 comes to rest in the cavity 31 of the needleprotecting tube 4.

FIG. 11, generally analogous with FIG. 7, shows the auto-injector in aposition in which the needle protecting tube 4 surrounds the injectionneedle 10 after the auto-injector has been removed from the surface ofthe tissue. In this embodiment, the locking tongue 25 is likewisearranged on the sliding sleeve 5. This enables a component to be omittedin the auto-injector. When the needle protecting tube 4 is advanced, thelocking tongue 25 grips behind the end edge of the needle protectingtube 4, such that the needle protecting tube 4 is secured againstretracting relative to the active agent container 7 or the slidingsleeve 5. When pressure is applied to the needle protecting tube 4 inthe proximal direction, the needle protecting tube 4 shifted togetherwith the sliding sleeve, the active agent container 7 and the injectionneedle 10, relative to the casing “C”.

In the foregoing description, embodiments of the present invention,including preferred embodiments, have been presented for the purpose ofillustration and description. They are not intended to be exhaustive orto limit the invention to the precise form disclosed. Obviousmodifications or variations are possible in light of the aboveteachings. The embodiments were chosen and described to provide the bestillustration of the principals of the invention and its practicalapplication, and to enable one of ordinary skill in the art to use theinvention in various embodiments and with various modifications as aresuited to a particular use contemplated. All such modifications andvariations are within the scope of the invention as determined by theappended claims when interpreted in accordance with the breadth they arefairly, legally, and equitably entitled.

1. An injection device comprising: an elongated casing; a containercarrying an injection needle, said container axially shiftable relativeto the casing; a piston which can be shifted in the container for thepurpose of forcing out a substance therein; a needle protecting tubeshiftable relative to the casing; and a latching member having at leasttwo positions, a latching position wherein the latching member preventsthe container from being shifted relative to the casing, and a releaseposition wherein the container is shiftable relative to the casing. 2.The injection device according to claim 1, wherein the needle protectingtube is shiftable generally into and out of the casing and whereinshifting the needle protecting tube into the casing moves the latchingmember from the latching position to the release position.
 3. Theinjection device according to claim 2, wherein a locking member isprovided for locking the needle protecting tube, said locking memberlocking the needle protecting tube in a position in which itsubstantially surrounds the injection needle after the injection devicehas been moved from a point of injection.
 4. The injection device as setforth in claim 3, further comprising a needle protecting cap for beingattached to the injection device, wherein attached to the injectiondevice, the needle protecting cap substantially encloses the injectionneedle prior to use prevents the needle protecting tube from being movedinto the casing.
 5. An auto-injector for automatically injecting anactive agent, comprising an elongated casing, an injection needle whichcan be shifted axially in the casing and connected to an active agentcontainer, a piston which can be shifted in the active agent containerfor the purpose of delivering the active agent, and a needle protectingtube which can be shifted relative to the casing, wherein, in a latchingposition, a latching member prevents the active agent container frombeing shifted with respect to the casing, and wherein that by shiftingthe needle protecting tube into the casing, the latching member is movedto a released position in which the active agent container is shiftablewith respect to the casing.
 6. The auto-injector as set forth in claim5, wherein in the latching position the latching member is locked by theneedle protecting tube.
 7. The auto-injector as set forth in claim 5,wherein the latching member is formed as at least one elasticallyflexible latching tongue.
 8. The auto-injector as set forth in claim 7,wherein the at least one latching tongue is arranged on a latchingsleeve mounted in the casing.
 9. The auto-injector as set forth in claim8, wherein the at least one latching tongue is formed integrally withthe latching sleeve.
 10. The auto-injector as set in claim 7, whereinthe latching tongue prevents the active agent container from beingshifted with respect to the casing by abutting a flange arranged on asliding sleeve which accommodates the active agent container, andwherein as the needle protecting tube is shifted into the casing itforces the latching tongue away from said flange.
 11. The auto-injectoras set forth in claim 5, wherein in the latching position, the latchingmember abuts a surface on the sliding sleeve which extends obliquelywith respect to the longitudinal axis of the auto-injector, via asurface extending obliquely with respect to the longitudinal axis of theauto-injector.
 12. The auto-injector as set forth in claim 11, whereinwhen the needle protecting tube is shifted into the casing, it releasesthe latching member and the latching member is forced out of thelatching position by advancing the sliding sleeve along the obliquesurfaces.
 13. The auto-injector as set forth in claim 5, wherein alocking member is provided for latching the needle protecting tube andlatches the needle protecting tube in a locked position in which itsubstantially surrounds the injection needle after the auto-injector hasbeen lifted from a point of injection.
 14. The auto-injector as setforth in claim 13, wherein, in the locked position, the needleprotecting tube and the active agent container can be shifted togetherrelative to the casing.
 15. The auto-injector as set forth in claim 12,wherein the locking member is formed as at least one elasticallyflexible locking tongue.
 16. The auto-injector as set forth in claim 15,wherein the at least one latching tongue and the at least one lockingtongue are arranged on the latching sleeve and are formed integrallywith the latching sleeve.
 17. The auto-injector as set forth in claim 5,further comprising a needle protecting cap for substantially sealing theneedle end of the auto-injector prior to use.
 18. The auto-injector asset forth in claim 17, wherein the needle protecting cap substantiallyencloses a portion of the active agent container.
 19. The auto-injectoras set forth in claim 17, wherein the needle protecting cap is formedsuch that when attached to the auto-injector, the needle protecting capprevents the needle protecting tube from being retracted into thecasing.
 20. The auto-injector as set forth in claim 17, wherein theneedle protecting cap comprises an inner sleeve extending over theactive agent container and an outer sleeve extending over the needleprotecting tube.